1. Complete Trailer brake system failure due to incorrect wire gauge used during assembly at Grand Design. 2. Frame failure at axle shackle weld on Lippert frame due to over-penetration. While towing the trailer there was a message on the tow vehicle information center ‘trailer Brakes disconnected’. All trailer breaking was lost while going down the Siskiyous. At that time the trailer began to sway and was difficult to maintain control due to the loss of trailer brakes. During assembly Grand Design used 18-gauge wire to connect the 14-gauge wire from the brake magnets and axle tube to the wire running through the trailer underbelly up to the Vehicle plug. Lippert brake installation manuals for 4 brake systems state to use at least 14-gauge wiring. These manuals are readily available on the Lippert website. The photos we have provided clearly show 18 gauge was used and its insulation had melted exposing the center conductor. Repair documentation from the dealership to fix the brakes indicated that the right rear magnet was intermittently bad drawing high current which would draw all the braking system current to that one assembly. This maximum current to one set of wiring caused the smaller 18-gauge wire to melt off its insulation which resulted in a hard short that prevented all braking at a very inopportune time. Had 14 gauge been used we would not have lost all braking to the trailer. During the brake wire repair at the dealership the frame around the RR axle shackle failed when the trailer was jacked up. It appears that the shackle attachment weld over-penetrated the frame ultimately causing a weak joint and lead to the frame failure. The frame failing around the shackle weld happening at the dealership instead of on the road is beyond lucky and avoided another very unsafe incident on the road. These two items happening at the same time almost resulted in a multi vehicle crash on I-5 southbound.